<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            height: 100vh;
        }
        .div {
            background-color: #FAFAFA;
            height: 300px;
            width: 300px;
        }
        button {
            width: 100px;
            height: 50px;
        }
    </style>
</head>

<body>
    
    <div class="div" onclick="divHandle(event)">
        <button onclick="btnHandle(event)">阿牛</button>
    </div>
</body>
<script>
    function btnHandle (e) {
        console.log('btn-target', e.target);
        console.log('btn-currentTarget', e.currentTarget);
    }
    function divHandle (e) {
        console.log('div-target       ', e.target);
        console.log('div-currentTarget', e.currentTarget);
        console.log('相等吗？', e.target === e.currentTarget)
    }
    // target: 指向事件触发的源标签
    // currentTarget: 指向事件绑定的标签
    // 如果点击的是事件绑定的标签，target === currentTarget
    // 否则，target标签一定是currentTarget标签的内部标签
</script>
</html>